Missing or empty input error

Question

I have this problem in my script but I don't have ideas for resolve this !

when I launch the script :

boak@boak-LX:~/Documents$ perl dl-sound.pl --url http://soundcloud.com/alexorion/bigger-room-radio-015
Missing or empty input at dl-sound.pl line 100.

the script :

sub fetch_music_info {
  my ($self, $music_url) = @_;

  $music_url ||= $self->{url};

  my $page = $self->_get_content($music_url);
  my $jsmusic = $1 if ($page =~ m{window.SC.bufferTracks.push\((.*)}i);
  $jsmusic =~ s/;//g if defined($jsmusic);
  $jsmusic =~ s/\)//g if defined($jsmusic);

  my $music_info = JSON::Tiny::decode_json($jsmusic);

  return $music_info;
}

Borodin · Accepted Answer · 2015-04-18 10:00:29Z

2

It is unlikely to he the cause of your problem, but you shouldn't make declarations conditional. The behaviour is undefined, and it can lead to all sorts of nonsense.

So this

my $jsmusic = $1 if $page =~ m{window.SC.bufferTracks.push\((.*)}i;

should be

my $jsmusic;
$jsmusic = $1 if $page =~ /window\.SC\.bufferTracks\.push\(([^)]*)/i;

Note also that I have changed the regex to escape the dots, and to capture only the characters up to the next closing parenthesis. That means the following substitutions shouldn't be necessary if I understand your data properly

Update

In fact, looking again, the whole purpose of your subroutine is invalidated if the pattern doesn't match, so you should write it more like

sub fetch_music_info {
  my ($self, $music_url) = @_;

  $music_url ||= $self->{url};

  my $page = $self->_get_content($music_url);
  if ($page =~ /window\.SC\.bufferTracks\.push\(([^)]*)/i) {
    return JSON::Tiny::decode_json($1);
  }
  else {
    die "Music Info not found";
  }
}

edited Apr 18, 2015 at 10:00

answered Apr 18, 2015 at 9:53

Borodin

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2 Comments

Boak Darkin Over a year ago

this solution doesn't resolve because the script returns all the time "Music Info not found" thank's for your reactivity @Borodin

Borodin Over a year ago

Well that just means that the regex pattern doesn't appear in the data. There's nothing much else the program can do! Perhaps your regex is wrong. Can you show a sample of the data you're trying to match?

Toto · Accepted Answer · 2015-04-18 09:44:42Z

1

I guess that $jsmusic is not defined here:

my $music_info = JSON::Tiny::decode_json($jsmusic);

Change to:

my $music_info;
$music_info = JSON::Tiny::decode_json($jsmusic) if defined $jsmusic;
return $music_info;

answered Apr 18, 2015 at 9:44

Toto

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Comments

Rich Daley · Accepted Answer · 2015-04-19 11:24:51Z

0

I agree with Borodin, but there's a more Perlish way to write this:

my ($jsmusic) = ($page =~ m{window.SC.bufferTracks.push\((.*)}i);

That's because the =~ operator returns a list of the matchvars ($1,$2, etc.).

In this case, $jsmusic will always be declared but it will be undefined if the regexp doesn't match. You need the parentheses around ($jsmusic) to force the operator to list context.

answered Apr 19, 2015 at 11:24

Rich Daley

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